High idle after battery died

[ViperC]

So I was going to get my car out and the battery was dead. I put it on charge for a couple of hours. When I attempted to start the car it fired right up. The only thing different was it was idling much higher than normal, around 1500-1750. It may have idled a little high before (~1000 rpm) on initial start for about 30 seconds, but it idled down to normal rpm soon after. Now it wont idle less than 1500 rpm. I even drove it for about 5 miles and every time I stopped it would continue to idle high. So, did the battery dying have something to do with this, because it's never done this before? Or has my IAC gone bad all of the sudden? I inspected the vacuum lines and everything seems to be ok, but I'm not ruling out a vacuum leak either.

[uvbnbit]

may need to clean the IAC.
how long was it dead? May also need a PCM re-set, reset Throttle position sensor.
How many miles?

[Steve-Indy]

Had this occur with our 97 last Fall...startled me!! That battery was a new Diehard Gold that died after a couple of months. Changed battery to Interstate Group 78 AGM, fired it up and all was well. Have almost eliminated Diehard Golds from our Vipers...as in my opinion, they are not what they were 20 years ago.

[ViperC]

may need to clean the IAC.
how long was it dead? May also need a PCM re-set, reset Throttle position sensor.
How many miles?

I had driven it in the 3 previous weeks, so it wasn't dead too long. I also reflashed it and it didn't help. It has right at 25,000 miles.

[ViperC]

Had this occur with our 97 last Fall...startled me!! That battery was a new Diehard Gold that died after a couple of months. Changed battery to Interstate Group 78 AGM, fired it up and all was well. Have almost eliminated Diehard Golds from our Vipers...as in my opinion, they are not what they were 20 years ago.

I wonder how a battery would effect the idle?

[GTS Dean]

Sometimes, the stepper motor for the IAC pintle has its PCM span values corrupted. It takes a few drive cycles to settle down.

[daveg]

^^^^^^^

[ViperC]

Sometimes, the stepper motor for the IAC pintle has its PCM span values corrupted. It takes a few drive cycles to settle down.

I'll try that out once the weather gets better again.

[jdeft1]

If it's a G1, (take a deep breath and let out slowly).

Run it it for a bit with the a/c on. Let the compressor cycle on/off a few times. That will help settle it out.

[ViperC]

Thanks for the help everyone! It finally started idling right.

[Viper98]

What was the culprit?

[ViperC]

What was the culprit?

I believe it stemmed from the battery dying. That's I can gather. I reflashed the computer with my SCT and drove it for a bit and it went back to normal. However, I have had a "service engine" light return again since the problem was solved and when I scanned the car it showed up as P0000. It doesn't provide any information on that code. What does that mean?

[98RedGTS]

I've had a random P0000 every now an then on my car as well. Tuned in to hopefully learn the causes of this. From what I've seen is that is the code the SCT provides when it doesn't have code in the tool for the error that is present.

[COI]

I've had a random P0000 every now an then on my car as well. Tuned in to hopefully learn the causes of this. From what I've seen is that is the code the SCT provides when it doesn't have code in the tool for the error that is present.

I have an idle problem every time the battery dies or gets too weak (generally as a result of forgetting to put the trickle charger on). For me, normally the idle is too low and it stalls. I certainly thought this is/was a known issue? After driving 10-20 minutes the idle/computer finds itself. If you search on some of the various Viper forums you'll see this is not uncommon. I've never had this issue last too long.